Grease: Live seems to have been both a critical success and a ratings one. It drew 12.2 million viewers — not as much as NBC's presentation of The Sound of Music, which had 18.3 million but more than The Wiz (11.5 million) and Peter Pan (9.2 million). The percentage of viewers in the 18-49 demographic category was also especially good. One presumes Fox will air their Grease a few more times. They'd better. They spent a reported $16 million on it.
I'm trying to think what show someone could do next that would have the same appeal. Hairspray and The Rocky Horror Show are already in the works. If I were deciding — and putting aside my own personal views of what's a great musical versus what isn't — I'd probably try to set up Mamma Mia. It has youth appeal and great sing-along tunes…and the plot would allow it to be opened up for a lot of spectacle, roaming over some studio's backlot. Plus, the movie did quite well.
And a little more time might need to pass since its movie but Jersey Boys could probably draw quite an audience.
Others? Thinking about shows with youth appeal might lead you to Tommy or Little Shop of Horrors. The latter with its small cast might not yield enough spectacle for some, plus there's the question of how you'd do the plant live in a way that wouldn't pale next to the one in the movie. But it's a funny-enough show that someone may give it a try.
It wouldn't surprise me if someone gave A Chorus Line a try, opening it up with live "flashbacks" to some of the stories told on that stage. It also wouldn't surprise me if they did and then realized that the show loses its intimate foundation when you do that and also interrupt every twelve minutes for commercials. Guys and Dolls doesn't have a lot of intrinsic appeal to younger viewers but it has great songs and if you cast it with the right young, well-known stars, it might soar.
And if Berry Gordy doesn't make Motown: The Movie out of the stage version, I could see that being a great live TV event.
That's about as far as my thoughts on this topic extend. Whatever anyone does, I hope they do it in front of a live audience. I wonder if the folks who did Grease: Live have a complete video of a dress rehearsal without all those audience members in place. That might make for a fascinating comparison. I'll bet it wasn't anywhere as fine a performance.